1. Field of the Invention
The invention relates to an apparatus and method for manufacturing magnetic heads and, more particularly, to the formation of a surface thereon.
2. Description of the Prior Art
A magnetic head element is mounted in a housing which presents a surface area to magnetic media. The exact shape of this surface area has gained in importance with the development of extremely small batch-fabricated head elements expected to read or write very small signals at very high densities. The final contouring of the housing surface establishes both the element's throat height (which critically affects the element's magnetic efficiency) and the aerodynamic characteristics of the head housing. The latter characteristics are essential to separate the head and media, thus reducing wear, yet keep them close enough together so as to not unnecessarily reduce the magnetic and electrical interaction between the head and media.
Solutions to the throat height problems are addressed in Abbott et al. U.S. Pat. No. 3,821,815, "Apparatus for Batch-Fabricating Magnetic Film Heads and Method Therefor", and L. A. Johnson et al. U.S. Pat. No. 3,921,340, "Magnetic Head Surface Formation Apparatus and Method", both assigned to International Business Machines Corporation. This application is directed to the problem of forming a complex plural-radius contour on the surface of the head housing. In Abbott et al., a single radius may be formed by lapping the head surface with a loop of abrasive tape. The length of radius may be changed, identically for each point along the length of the head housing, by oscillating the housing against a grinding wheel under the control of an appropriately shaped cam. A more complex spherical surface contour is achieved in L. A. Johnson et al. by spinning the head continuously against a contoured abrasive wheel.
Recent head designs, such as shown in Freeman et al. U.S. Pat. No. 3,821,813, "Wasp-Waist Head for Flying Flexible Magnetic Storage Medium Over Head", assigned to International Business Machines Corporation, require even more complex contours which must be repeatedly reproducible without variation from sample-to-sample. Further, development of advanced head designs makes it desirable to be able to reproduce head contours identical to previously produced contours except in specified variable parameters. It is also desirable to make the specification of contour parameters independent of other surface related head dimensions, such as throat height.